How do I cut crown molding for a corner that is not 90 degrees?

Measure the exact corner angle with a digital angle finder, then enter that angle into a crown molding angle calculator along with your spring angle. The calculator will compute the exact compound miter and bevel angles for your non-90-degree corner. Never assume a corner is exactly 90 degrees — most real walls vary by 1 to 3 degrees.

What are the crown molding angles for a 45 degree corner?

For a 45-degree inside corner with 38-degree spring angle crown molding laying flat, the miter angle is approximately 18.43 degrees and the bevel angle is approximately 18.08 degrees. Use the Crown Molding Angle Calculator to get exact settings for your specific spring angle.

How do I measure a corner angle for crown molding?

The easiest method is to use a digital angle finder or electronic bevel gauge. Open the tool and press both arms flat into the corner at the wall level where the crown molding will sit. Read the angle displayed. You can also use two straightedges and a protractor to measure the opening angle, then enter that value into the calculator.

What if my room corners vary in angle throughout the room?

Each corner should be measured individually. It is common for corners in the same room to vary by several degrees. Measure each corner before cutting the piece for that corner, and use the calculator to get specific angles for each one.

Crown Molding Angles for Non-90° Corners

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Most Corners Are NOT 90 Degrees

This is the most common surprise for first-time crown molding installers: even in new construction, most "square" corners measure anywhere from 88° to 92°. In older homes they can vary even more. Using the standard 90° angles in these situations causes gaps — sometimes visible gaps — at the joint.

The solution is simple: measure every corner before you cut, then plug the exact angle into the Crown Molding Angle Calculator to get precise settings.

⚠️ Never Assume 90° Even a 1-degree error produces a visible gap on an inside corner. A 2-degree error creates a gap you can see from across the room. Always measure — it takes 30 seconds and saves hours of frustration.

How to Measure Your Corner Angle

Use a digital angle finder (also called a digital bevel gauge). These cost $15–$30 at any hardware store and are the most accurate tool for this job.
Open the angle finder and press both arms flat against the two walls, at the height where the crown molding will sit (about 6 inches down from the ceiling).
Read the angle displayed on the screen. This is your actual corner angle — enter this into the calculator instead of 90.
Alternative method: Hold two straight boards against each wall so they cross in the corner, trace the V-shape onto paper, and measure the angle with a protractor.

Angle Tables for Common Non-90° Corners

Quick Reference — Most Common Non-90° Corners

Find your measured angle below — get your exact saw settings instantly

38° spring angle · flat cut · inside corner — full table below

These tables show the compound miter and bevel settings for common corner angles, cutting crown molding laying flat. For any angle not listed, use the Crown Molding Angle Calculator.

38° Spring Angle (Most Common)

Corner Angle	Miter (Inside)	Bevel (Inside)	Miter (Outside)	Bevel (Outside)
85°	29.82°	32.13°	29.82°	32.13°
87°	30.52°	32.85°	30.52°	32.85°
88°	30.87°	33.20°	30.87°	33.20°
89°	31.23°	33.56°	31.23°	33.56°
90° (Standard)	31.62°	33.85°	31.62°	33.85°
91°	32.01°	34.15°	32.01°	34.15°
92°	32.40°	34.50°	32.40°	34.50°
93°	32.77°	34.83°	32.77°	34.83°
95°	33.51°	35.47°	33.51°	35.47°
135° (Bay/Octagon)	13.62°	15.74°	13.62°	15.74°

45° Spring Angle

Corner Angle	Miter (Inside)	Bevel (Inside)	Miter (Outside)	Bevel (Outside)
88°	33.60°	28.77°	33.60°	28.77°
89°	34.43°	29.38°	34.43°	29.38°
90° (Standard)	35.26°	30.00°	35.26°	30.00°
91°	36.09°	30.61°	36.09°	30.61°
92°	36.91°	31.21°	36.91°	31.21°
135° (Bay/Octagon)	15.00°	13.26°	15.00°	13.26°

💡 Note on Inside vs Outside Miter Direction The miter and bevel angle values are the same for inside and outside corners — what changes is the molding orientation on the saw and the direction you rotate the turntable. Select the correct corner type in the calculator for saw position instructions.

Bay Windows and Angled Walls

Bay windows typically have two 45° corners (walls meeting at 135°) or two 30° corners (walls at 150°). These are among the most common non-90° installations. The table above includes 135° settings — for other bay window angles, use the calculator.

What If Each Corner in the Room Is Different?

This is very common, especially in older homes. The solution is to measure and calculate each corner individually rather than assuming they're all the same. It adds a few minutes per corner but guarantees tight joints throughout the room.

How to Fix a Gap in a Crown Molding Corner

If you've already cut and installed crown molding and there's a visible gap at the joint, don't panic — there are two scenarios and a fix for each.

Gap Caused by Wrong Corner Angle (Most Common)

This happens when you assumed 90° but the corner measured differently. The fix:

Measure the actual corner angle with a digital angle finder.
Recalculate using the Crown Molding Angle Calculator with the real angle.
Recut one piece — usually only one side needs adjusting by 1–2°.
If the gap is small (under 2mm) — fill with paintable caulk, smooth with a wet finger, paint. Once painted, gaps under 2mm are invisible.

Gap Caused by an Out-of-Flat Wall

Sometimes the corner angle is correct but the wall bows or dips behind the molding, creating a gap along the length of the piece (not just at the joint). Fix:

Run a bead of paintable caulk along the wall and ceiling edges — this is standard professional finishing on every installation.
For larger gaps — add a thin shim behind the molding at the low point before nailing, then caulk.
Back-cut the molding — a slight 1–2° back bevel on the wall-contact face lets only the front edge touch, eliminating rocking on uneven walls.

⚠️ Caulk Is Not a Cover-Up — It's the Standard Finish

Every professional crown molding installation ends with caulk along the wall and ceiling edges. Even perfect cuts get caulked. It seals the edge, hides minor imperfections from wall texture, and creates a cleaner painted finish. If your gap is under 3mm, caulk is the correct professional solution — not a workaround.

Frequently Asked Questions

My corner measured 91.5° — can I just use 91° or 92° settings?

You can round to the nearest degree for a rough estimate, but for best results enter 91.5 directly into the Crown Molding Angle Calculator which accepts decimal values. A half-degree error is noticeable on an outside corner joint.

How do I measure a corner angle without a digital angle finder?

Place two straight boards against each wall so they cross at the corner, tape them together to hold the angle, then lay the V-shape flat and measure the opening angle with a protractor. Alternatively, trace the shape onto cardboard and measure from there.

What tools do I need to measure corner angles accurately?

A digital angle finder (bevel gauge) is the most accurate and easiest tool at around $15–$30. A sliding T-bevel with a protractor also works. Avoid eyeballing or using a standard square — small errors cause large gaps in the finished joint.

🔨 Calculate Your Exact Corner Angles

Enter any corner angle — 88°, 91°, 135°, or anything else — to get precise miter and bevel settings instantly.

Open the Calculator

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